A three-year program consisting of experiments with humans and animals is proposed. The aim of this program is to obtain new information about the effects of marihuana on interpersonal behavior as well as on neurobiological, biochemical, and anatomical parameters. The interpersonal behaviors will be studied with respect to drug effects on physical aggression under controlled laboratory conditions. Delta-9-Tetrahydrochannabinol (THC), the major active principle of marihuana will be used in all studies. Dose and time-course information will be obtained, as well as information generated by neurophysiological (EEG, gross evoked response, EKG) and metabolic studies. Preliminary evidence indicates that delta-9-THC can inhibit the aggressive response to physical attack. Ethanol tends to enhance such aggression. The proposed research will attempt to determine mechanisms of the marihuana effect by manipulating motivational, cognitive, and pharmacological parameters. Objective data will be supplemented by clinical assessments of personality variables. Experiments with rats and mice also will investigate the mechanisms of aggression inhibition by THC. This research will deal with the apparent estrogenic activity of the compound by analyzing its effects on serum hormone levels and morphology of gonadal hormone target organs. Effects on THC on testes, ovaries, breast tissue and adrenal glands will be investigated using histological and biochemical techniques. Standard behavioral methods will be used to asess the effects on spontaneous aggression of THC administered directly to adults or indirectly to offspring through mammary and placental transfers.